1. Field of the Invention
The present invention relates to a work cutting apparatus and a work cutting method, and more specifically to a work cutting apparatus and a work cutting method utilizing a cutting blade having a surface containing a super hard abrasive grain dispersed entirely therein.
2. Description of the Related Art
Conventionally, an electrocast cutting blade having a small blade thickness is proposed as a cutting blade capable of reducing an amount of removed material cut from a work. This cutting blade is formed, as disclosed in the Japanese Patent Publication (of examined Application for opposition) No. 6-49275 for example, by dispersing a super hard abrasive grain made of such a material as diamond, cBN and so on in a metal plate phase of Ni and Co. The cutting blade is primarily used for cutting a substrate for a magnetic head.
When the cutting blade is used to cut a hard, brittle and thick work such as a rare-earth magnet member, an amount of projection of the cutting blade must be increased. However, due to reasons such as the small thickness of the blade, rigidity of the cutting blade decreases, sometimes causing the cutting blade to deform during the cutting, resulting in decrease in cutting accuracy.
Further, when the work is cut by using such a cutting blade as described above, there is only a small difference between a thickness in an outer circumferential portion and a thickness in a center portion of the cutting blade. Thus, there is only a small clearance essential to supply coolant to a cutting region of the work. Therefore, if a section of the work to be made by the cutting has a large area, and especially if a deep groove is cut in the work during the cutting operation, it becomes impossible to sufficiently supply the coolant to the cutting region, causing the cutting blade to be seized easily, resulting in a problem of shortened life of the cutting blade.
It is therefore a primary object of the present invention to provide a work cutting apparatus and a work cutting method capable of improving cutting accuracy even when cutting the work which has a relatively large thickness.
Another object of the present invention is to provide a work cutting apparatus and a work cutting method capable of increasing the life of the cutting blade.
According to an aspect of the present invention, there is provided a work cutting apparatus for cutting a work, comprising: a cutting blade having a surface containing a super hard abrasive grain dispersed entirely therein; first driving means for rotation of the cutting blade; and second driving means for moving at least one of the cutting blade and the work in a direction in which movement of the cutting blade relative to the work at a time of cutting is vertical to the work.
According to another aspect of the present invention, there is provided a work cutting method for cutting a work, comprising: a first step of preparing a cutting blade having a surface containing a super hard abrasive grain dispersed entirely therein; and a second step of cutting the work with the cutting blade by rotating the cutting blade and moving at least one of the cutting blade and the work in a direction in which movement of the cutting blade relative to the work is vertical to the work.
According to the present invention, for example, by lowering the rotating cutting blade thereby cutting into the work disposed at a predetermined position, a force acting to deform the cutting blade can be decreased and therefore a load exerted to the cutting blade is decreased. Further, dynamic rigidity of the cutting blade can be increased if the cutting blade is rotated at a high speed. Therefore, the cutting blade becomes less susceptible to deformation, and thus it becomes possible to stabilize the cutting and improve cutting accuracy even if the work to be cut has a relatively large thickness.
According to another aspect of the present invention, there is provided a work cutting apparatus for cutting a work, comprising: a cutting blade having a surface containing a super hard abrasive grain dispersed entirely therein; first driving means for rotation of the cutting blade; and second driving means for moving at least one of the cutting blade and the work in a direction in which movement of the cutting blade relative to the work at a time of cutting is along a normal line passing a tangential point between the cutting blade and the work.
According to still another aspect of the present invention, there is provided a work cutting method for cutting a work, comprising: a first step of preparing a cutting blade having a surface containing a super hard abrasive grain dispersed entirely therein; and a second step of cutting the work with the cutting blade by rotating the cutting blade and moving at least one of the cutting blade and the work in a direction in which movement of the cutting blade relative to the work is along a normal line passing a tangential point between the cutting blade and the work.
According to the present invention, for example, by cutting into the work disposed at a predetermined position, with the rotating cutting blade along a normal line passing a tangential point with the work, the cutting blade becomes less susceptible to deformation as in the invention described above, making possible to improve cutting accuracy even if the work to be cut has a relatively large thickness.
According to another aspect of the present invention, there is provided a work cutting apparatus for cutting a work, comprising: a container holding a coolant for submerging the work, a cutting blade having a surface containing a super hard abrasive grain dispersed entirely therein; first driving means for rotation of the cutting blade; and second driving means for moving at least one of the cutting blade and the work for cutting the work submerged in the coolant.
According to still another aspect of the present invention, there is provided a work cutting method for cutting a work, comprising: a first step of preparing a cutting blade having a surface containing a super hard abrasive grain dispersed entirely therein; and a second step of cutting the work submerged in the coolant with the cutting blade by rotating the cutting blade and moving at least one of the cutting blade and the work.
According to the present invention, since the cutting is made to the work submerged in the coolant, the coolant can be supplied sufficiently to the cutting region even if the clearance between the work and the cutting blade, which is essential for supplying the coolant to the cutting region of the work, is small. As a result, seizure of the cutting blade can be prevented, making possible to increase the life of the cutting blade.
Preferably, the coolant is also supplied positively to the work. When the cutting blade is rotated at a high speed, an airflow accompanying the rotating cutting blade removes the coolant from a surface of the work for example, sometimes making impossible to supply the coolant sufficiently to the cutting region. However, by supplying the coolant positively to the work, the work can be sufficiently submerged in the coolant, preventing the seizure of the cutting blade more reliably.
Further, preferably, a plurality of the cutting blades and a spacer including two main surfaces each having an outer circumferential portion formed with an annular stepped portion are prepared, and the spacer is inserted between two mutually adjacent cutting blades. In the cutting blade having the surface containing the super hard abrasive grain dispersed entirely therein, if an area of contact between the cutting blade and the spacer is large, the number of the abrasive grains contacting the spacer increases, which sometimes increases an amount of tilt of the cutting blade. However, by using a spacer having the annular stepped portions as described above, the area of contact between the spacer and the super hard abrasive grains dispersed in a side surface of the cutting blade is decreased, decreasing the amount of tilt of the cutting blade when the cutting blade is attached.
Further, preferably, the cutting blade is formed by means of electrocasting for example, and includes a metal plate phase containing the super hard abrasive grain dispersed thereon. This provides a desired cutting blade having a small blade thickness, making possible to reduce the amount of material ground off the work.
Preferably, a cutout is formed in a tip portion of the cutting blade. This helps supplying the coolant to a cutting edge of the cutting blade, resulting in reduced dimensional inconsistency of a member obtained by cutting the work.
Further, preferably, the cutting blade is rotated at a high speed not slower than 8000 rpm. This can centrifugally increase dynamic rigidity of the cutting blade. Therefore, the cutting blade is not distorted during the cutting, and thus side surfaces of the cutting blade do not contact the work during the cutting. As a result, cutting accuracy can be maintained and the seizure of the cutting blade can be eliminated, increasing the life of the cutting blade.
Further, preferably, the work is vibrated at the time of cutting, in a direction parallel to a main surface of the cutting blade. With this arrangement, the cutting blade can be periodically spaced from the cutting region, making easier to supply the coolant to the cutting region. Further, the cutting blade is allowed to come back from a deformed state to a correct state, making possible to improve the cutting accuracy.
Preferably, a vibrating direction of the work is perpendicular to the direction of movement of the cutting blade relative to the work. With this arrangement, it becomes possible to further reduce the cutting load exerted to the cutting blade. Therefore, the cutting blade becomes less susceptible to deformation, making possible to improve the cutting accuracy.
The present invention is especially effective if the work is a rare-earth alloy magnet member which is hard, brittle and difficult to cut.
The above objects, other objects, characteristics, aspects and advantages of the present invention will become clearer from the following description of embodiments to be presented with reference to the accompanying drawings.